Hello dear motorists and blog readers. Today the topic of “driving style” will be touched upon. I hope it helps to keep long kilometers to her capital. Every time, drivers ask the question: at what speed is it better to drive a car, high or low?
And so, engines internal combustion are divided into 2 types:
1.Slow-moving(for example, Moskvich 2141)
2.high speed(from - to priors and grants)
The first type of engine is low-speed, designed for traction, and not for spinning the engine to achieve top speed. He looks like diesel type. Maximum torque is reached at low rpm (for ) (approx. 2500 rpm)
In high-speed power units, the peak torque falls in the range 3500-4500 rpm. Therefore, the car pulls better at high speeds.
What does driving at low speeds lead to?
Why all these numbers. The fact is that a high-speed type of engine, when operating at low speeds, experiences:
1.Oil starvation. The oil pump is not delivering oil well high speed, and at this time, bearings (liners crankshaft). Because of low pressure oil, it poorly lubricates the rubbing parts of the engine and over time they begin to rub “metal on metal”, which can lead to overheating and jamming of the main mechanisms of the power unit.
2.Carbon deposits form in the combustion chamber. Gasoline does not burn completely, candles, nozzles are clogged. 
3.Camshaft under load. Piston fingers begin to knock.
4. Detonation occurs, i.e. gasoline explodes before it should (self-ignition), huge pressure on piston group. The engine twitches, it heats up more.
. The box is poorly lubricated and works under load due to tight driving.6. . At low revs, in order to accelerate, the “gas” pedal is pressed more than if the engine was spinning, therefore, the additional enrichment of the mixture - hence the greater consumption.
7.Low throttle on the road. In cases of occurrence dangerous situation, it is impossible to quickly accelerate.
I must have scared you, now I get the impression that you only need to ride high revolutions. No, on high, also the load on all components of the car ( , ). The most acceptable ride medium speed. In general, you need to listen to the engine, feel the traction. If you go down the hill (“gas” is released), then the speed 1500-2000 rpm not harmful, because the power unit does not work “retracted”.
The main factors of driving at medium speeds (middle speeds in the range (2800-4500rpm))
- The engine runs without loads;
- Can pick up speed easily
- The accelerator pedal is pressed less, therefore, and less consumption fuel;
- The fuel burns completely, no carbon deposits are formed in the cylinders;
In order to keep the engine in “shape”, it is sometimes useful to spin it up to maximum speed,
so that he self-cleansed from carbon deposits in the cylinders, so to speak, “sneezed”.
Many say: “at idle, the engine is normally lubricated, which means you can ride them or a little higher than XX”.
Do not forget that at XX the engine is running without loads. In many books for car operation it is written that it is undesirable to run the engine, more 15-20 min on XX.
Ride carefully, without forcing the engine, and then it will serve you for many years.
That's all, until we meet again.
Almost every driver is well aware that the resource of the engine and other components of the car directly depends on the individual driving style. For this reason, many car owners, especially beginners, often think about what speed is best to drive. Next, we will consider what engine speeds you need to keep, taking into account different road conditions during vehicle operation.
Read in this article
Engine life and revs while driving
Let's begin with competent operation and constant maintenance of optimal engine speed allows you to increase engine life. In other words, there are operating modes when the motor wears out the least. As already mentioned, the service life depends on the driving style, that is, the driver himself can conditionally "regulate" given parameter. Note that this topic is the subject of discussions and disputes. More specifically, drivers are divided into three main groups:
- the former include those who operate the engine at low speeds, constantly moving "pulled".
- the second should include such drivers who only periodically spin up their motor to above-average speeds;
- the third group is considered to be car owners who constantly maintain the power unit in a mode above medium and high engine speeds, often driving the tachometer needle into the red zone.
Let's understand in more detail. Let's start with driving on the "bottom". This mode means that the driver does not raise the speed above 2.5 thousand rpm. on gasoline engines and holds about 1100-1200 rpm. on diesel. This style of driving has been imposed on many since the days of driving school. Instructors authoritatively state that it is necessary to drive at the lowest speeds, since in this mode biggest savings fuel, the engine is least loaded, etc.
Note that in driving courses it is advised not to turn the unit, since one of the main tasks is maximum safety. It is quite logical that low rpm in this case are inextricably linked with driving at low speeds. There is logic in this, since slow and measured movement allows you to quickly learn how to drive without jerks when shifting gears on cars with manual transmission, teaches a novice driver to move in a calm and smooth mode, provides more confident control over the car, etc.
Obviously, after receiving driving license this driving style is further actively practiced on own car turning into a habit. Drivers of this type they begin to get nervous when the sound of a hyped motor begins to be heard in the cabin. It seems to them that the increase in noise means a significant increase in the load on the internal combustion engine.
As for the engine itself and its resource, too “sparing” operation does not add to its service life. Moreover, everything happens exactly the opposite. Imagine a situation when a car is moving at a speed of 60 km / h in 4th gear on even asphalt, the speed is, say, about 2 thousand. In this mode, the engine is almost inaudible even at budget cars fuel consumption is minimal. At the same time, there are two main disadvantages in such a ride:
- it is almost completely impossible to accelerate sharply without switching to downshift, especially on "".
- after changes in the road surface, for example, on slopes, the driver does not downshift. Instead of shifting, he simply presses harder on the gas pedal.
In the first case, the motor is often outside the “shelf”, which does not allow you to quickly disperse the car if necessary. As a result, this driving style affects general security movement. The second point directly affects the engine. First of all, driving at low revs under load with a strongly depressed gas pedal leads to detonation of the motor. The specified detonation literally breaks the power unit from the inside.
In terms of consumption, the savings are almost completely absent, since a stronger pressure on the gas pedal on overdrive under load causes enrichment fuel-air mixture. As a result, fuel consumption increases.
Also, “pull-in” driving increases engine wear even in the absence of detonation. The fact is that at low speeds, the loaded rubbing parts of the motor are not sufficiently lubricated. The reason is the dependence of the performance of the oil pump and the pressure it creates. engine oil in from all the same engine speeds. In other words, plain bearings are designed to operate under hydrodynamic lubrication conditions. This mode involves the supply of oil under pressure into the gaps between the liners and the shaft. This creates the desired oil film, which prevents wear of the mating elements. The effectiveness of hydrodynamic lubrication is directly related to engine speed, that is, the higher the speed, the higher the oil pressure. It turns out that with a heavy load on the engine, taking into account the low speed, there is a high risk of severe wear and breakage of the liners.
Another argument against driving at low speeds is a reinforced engine. In simple words, with a set of revolutions, the load on the internal combustion engine increases and the temperature in the cylinders rises significantly. As a result, part of the soot simply burns out, which does not happen when permanent operation on the "bottom".
High engine speed
Well, you say, the answer is obvious. The engine needs to be revved more strongly, as the car will respond confidently to the gas pedal, it will be easy to overtake, the engine will be cleaned, fuel consumption will not increase so much, etc. This is true, but only in part. The fact is that constant driving at high speeds also has its drawbacks.
High turnovers can be considered those that exceed the approximate figure of about 70% of the total number available for gasoline engine. With the situation is slightly different, since units of this type are initially less revving, but have a higher torque. It turns out that high revolutions for engines of this type can be considered those that are behind the “shelf” of diesel torque.
Now about the engine resource with this driving style. Strong spinning of the engine means that the load on all its parts and the lubrication system increases significantly. The temperature indicator also increases, additionally loading. As a result, engine wear increases and the risk of engine overheating increases.
It should also be borne in mind that at high speed modes, the requirements for the quality of engine oil increase. Lubricant should provide reliable protection, that is, meet the declared characteristics for viscosity, oil film stability, etc.
Ignoring this statement leads to the fact that the channels of the lubrication system when constant driving at high RPMs, they can clog up. This happens especially often when using cheap semi-synthetics or mineral oil. The fact is that many drivers change the oil not earlier, but strictly according to the regulations or even later than this period. As a result, the liners are destroyed, disrupting the operation of the crankshaft and other loaded elements.
What speed is considered optimal for the motor
To save engine life, it is best to drive at such speeds, which can conditionally be considered average and slightly above average. For example, if the “green” zone on the tachometer suggests 6 thousand rpm, then it is most rational to keep from 2.5 to 4.5 thousand rpm.
In the case of atmospheric internal combustion engines, designers try to fit the torque shelf in this range. Modern turbocharged units provide confident traction at lower engine speeds (the torque shelf is wider), but it is still better to spin the engine a little.
Experts claim that optimal modes work for most motors is an indicator from 30 to 70% of maximum number rpm while driving. Under such conditions power unit minimal damage is done.
Finally, we add that it is periodically desirable to spin up a well-heated and serviceable motor with quality oil by 80-90% when driving on flat road. In this mode, it will be enough to drive 10-15 km. Note that this action do not need to be repeated often.
Experienced motorists recommend spinning the engine almost to the maximum once every 4-5 thousand kilometers traveled. This is necessary for different reasons, for example, so that the cylinder walls wear out more evenly, since with constant driving only at medium speeds, a so-called step can form.
Read also
Setting the idle speed on the carburetor and injection motor. Features of the XX carburetor adjustment, idle adjustment on the injector.
Roar under the hood - is it scary? On the tachometer, the red zone starts at X rpm. What revolutions can be counted (of course we are talking about intervals):
- normal
- optimal (in terms of consumption, resource, etc.)
- acceptable (one-time, at short intervals, at large)
- marginal
- unacceptable
Without going into too much detail, there are 2 main sources of RPM-related engine damage:
As for strength, for correct assembled engine it can withstand the maximum speed prescribed by the manufacturer without harm (the red zone of the tachometer) + another 10% - easily. The danger of "twisting" the engine, as a rule, exists on an unloaded engine (well, for example, if the gas pedal is "sunk" in neutral). When driving with the gear engaged, when "twisting" there are "special effects", such as: separation of valves from the camshaft cams, "weighted" state piston rings, violations in the chopper - mainly related to the inertia of non-rotationally moving parts. In addition, when "twisting" the engine power drops sharply. All this taken together sharply reduces the intensity of acceleration and makes it clear that there is simply no point in “turning” higher, and it will encourage you to shift gears up. In this case, the engine will not receive any significant damage.
- Problems related to the strength limits of parts;
- Dependence of oil pressure on the number of revolutions.
In general, it would be more correct to talk about engine hours, and even more correct - about engine hours multiplied by the average load (as regards the effect of the number of revolutions on the durability and mechanical strength of parts).
Now for the oil pressure. Here the source of "harm" is the low engine speed, or rather the speed at which the pressure reducing valve is still closed. oil pump(this valve opens when the estimated oil pressure is reached - approximately 3.5 kg) Of course, the oil pressure depends, in addition to the number of revolutions, also on the viscosity of the oil, its temperature, etc., let's omit these parameters for now. The first main point is that when the calculated oil pressure is reached, the "harm" to the engine from the number of revolutions is minimal. The second point - the maximum damage to the engine is applied to idling as well as when starting and stopping it.
Automakers have to put up with this, as the complete solution to this problem is autonomous electric drive when the oil pressure reaches the calculated value before the engine is started. However, this is very expensive.
A partial solution is to increase the capacity of the oil pump (usually by increasing the height of the gears).
However, I digress.
The oil pressure depends, in addition to the number of revolutions, also on the total cross-sectional area through which the oil flows out (in the main and connecting rod bearings, mostly). These sections increase with time, and the "harmless number of revolutions" shifts "up".
Main conclusions:
- "Twisting" is not harmful, "twisting" is not worth it.
- It's always better to drive at a slightly higher RPM than is accepted by most drivers.
- If the red oil pressure lamp does not go out immediately when starting the engine, change the oil filter.
